docs: def datacenters(gandi, id):
      """List available datacenters."""
      output_keys = ['iso', 'name', 'country', 'dc_code', 'status']
      if id:
          output_keys.append('id')
  
      result = gandi.datacenter.list()
      for num, dc in enumerate(result):
          if num:
              gandi.separator_line()
          output_datacenter(gandi, dc, output_keys, justify=10)
  
      return result